Add chvgpio driver for gpio present of Intel z8000 series (Cherry View) SOC

[thj]

Summary

Add chvgpio that supports the gpio driver found on Intel z8000 series system on chips.
This driver is based on the chvgpio driver from OpenBSD heavily refactored to match
FreeBSD gpio subsystem.

This revision does not support the interupt mechanisms on the gpio controller. The
hardware I have requires other devices drivers before I will be able to test these.

There is a test program here:
https://github.com/adventureloop/gpdpocket/blob/master/gpdfand.sh

that controls the gpio connect fan in my Cherryview laptop (GPD Pocket)

[rpokala]

Is the name correct?

https://ark.intel.com/search?q=Cherry+View -- nothing found.
https://ark.intel.com/search?q=Atom+Z8 -- finds several "Processor X Series" chips; click one, and it lists the codename as "Cherry Trail".

[thj]

In D13086#272907, @rpokala wrote:

Is the name correct?

https://ark.intel.com/search?q=Cherry+View -- nothing found.
https://ark.intel.com/search?q=Atom+Z8 -- finds several "Processor X Series" chips; click one, and it lists the codename as "Cherry Trail".

I think this is particularly confusing. My understanding is that Intel changed the platform code name from Cherry Trail to 'Products formerly Cherry Trail' as seen here:
https://ark.intel.com/products/codename/46629/Cherry-Trail

The other implementations of this gpio controller refer to the codename as CherryView (sans space) as can be seen here:
https://github.com/torvalds/linux/blob/master/drivers/pinctrl/intel/pinctrl-cherryview.c
https://github.com/openbsd/src/blob/master/sys/dev/acpi/chvgpio.c

With OpenBSD using CherryView in the man page for the device:
https://man.openbsd.org/chvgpio.4

I don't really know which is the correct name to use with these devices, but I would favour consistency across platforms.
I would like to keep the driver name inline with OpenBSD so that the same devices attach on the same hardware.

[wblock]

share/man/man4/chvgpio.4

39

This will read a little weird: "The chvgpio is a driver..."

I suggest removing "The".

40

is a driver for the GPIO controller in Intel's Cherry View System on Chip

43

The Cherry View...

45

Needs markup on the device name, possibly .Pa:

All but VIRTUAL are exposed to userland as
.Pa /dev/gpiocN ,
where N is 0-3.

[thj]

Remove #if 0'd code.

Update chvgpio.4 based on comments.

[wblock]

share/man/man4/chvgpio.4

42

This still needs a "The" at the beginning of the sentence.

The Cherry View SoC has 5 banks of GPIO pins, NORTH, EAST, SOUTHEAST, SOUTHWEST and

[thj]

Add leading 'The'

[gonzo]

Code part looks good to me